Radio-infrared supernebulae in II Zw 40

Sara C. Beck*, Jean L. Turner, Laura E. Langland-Shula, David S. Meier, Lucian P. Crosthwaite, Varoujan Gorjian

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


We report subarcsecond-resolution Very Large Array and Keck mid-infrared imaging of the dwarf starburst galaxy II Zw 40. II Zw 40 contains a bright compact thermal radio and infrared source with all the characteristics of a collection of dense H II regions ionized by at least 14,000 O stars. The supernebula is revealed to consist of multiple sources within an envelope of weaker emission. The radio emission is dominated by free-free emission at 2 cm, and the spectrum of this emission appears to be rising. This suggests that the free-free emission is optically thick at 2 cm and that the individual H II regions are ∼1 pc in size. This complex of "supernebulae" dominates the total infrared luminosity of II Zw 40, although the radio source is less than ∼150 pc in diameter. Multiple super-star clusters appear to be forming here, the much larger analogs of large Galactic H II region complexes.

Original languageEnglish
Pages (from-to)2516-2523
Number of pages8
JournalAstronomical Journal
Issue number5 1763
StatePublished - Nov 2002


  • Galaxies: dwarf
  • Galaxies: individual (II Zw 40)
  • Galaxies: star clusters
  • Galaxies: starburst
  • Radio continuum


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